Anti-wear oil additives



United States Patent 3,273,981 ANTI-WEAR OIL ADDITIVES Michael J. Furey,Berkeley Heights, N.J., assignor to Esso Research and EngineeringCompany, a corporation of Delaware N0 Drawing. Filed July 16, 1963, Ser.No. 295,546 7 Claims. (Cl. 44-66) The present application is acontinuation-in-part of Serial No. 263,425, filed March 7, 1963,entitled Oil Compositions Containing Anti-Wear Additives, now Patent No.3,180,832, inventor, Michael I. Furey, which, in turn, is acontinuation-in-part of Serial No. 816,704, filed May 29, 1959, entitledOil Compositions Containing Anti-Wear Additives, now abandoned,inventor, Michael J. Furey.

The present invention is generally concerned with a novel class oflubricity additive mixtures, additive concentrates, and oleophilicliquid compositions containing these additive mixtures. The invention ismore specifically concerned with improving the lubricity of hydrocarbonliquids such as gasolines, aviation turbo fuel, kerosene, diesel fuel,lubricating oil and mineral lubricating oils. Other base fluids includeliquid carbohydrates and esters such as dioctyl sebacate and didecyladipate. The present invention also contemplates the use of thelubricity additive mixtures in solid products such as paraffin wax,lubricating grease and Carbowax. The invention in one specific aspectrelates to improving the lubricity of middle distillates, particularlyjet fuels. The lubricity additive mixtures of the present inventioncomprise a dicarboxylic acid and a partial ester of a polyhydricalcohol.

The lubricity additive mixtures of the present invention preferablycomprise a partial ester of a polyhydric alcohol, and dicarboxylic acidsthat are obtained by the polymerization of dienoic or trienoicmonocarboxylic acids. Thus, the invention is concerned with a novelclass of lubricity additive mixtures which are specifically adapted foruse in conjunction with oleophilic liquids such as hydrocarbonlubricants and jet fuels. In accordance with a specific adaptation ofthe present invention, middle distillate compositions such as jet fuelsare improved with respect to their lubricity by incorporating therein aneffective amount of a mixture of a partial ester of a polyhydricalcohol, and a dimer of linoleic acid.

Many oil compositions are designed for lubricating under boundaryconditions (e.g. crankcase oils, aviation oils and gear oils) where theprevention of wear of the metal surfaces under heavy loading is aserious problem. One common example of such heavy loading occurs in theoperation of the valve lifter mechanism of gasoline engines. Here,pressures of 50,000 to 100,000 p.s.i. can occur between the valve lifterand its actuating cam, and metal Wear is accordingly high. It has nowbeen found that metal wear can be significantly reduced by adding to anoleophilic liquid such as a mineral oil lubricant, a mixture of adicarboxylic acid and a partial ester of a polyhydric alcohol. It ispreferred that the dicarboxylic acid be characterized by having at least9 carbon atoms, preferably 12 to 42 carbon atoms, between the respectivecarboxylic groups. A particularly desirable mixture is a dimer acid suchas linoleic dimer and sorbitan monooleate.

Other additives, of course, may be added to the oil compositions of thepresent invention to form a finished oil. Such additives includeoxidation inhibitors such as phenot-hiazine or phenyl a-naphthylamine;rust inhibitors such as lecithin or petroleum sulfonates; detergentssuch as the barium salt of isononyl phenol sulfide; pour pointdepressants such as copolymers of vinyl acetate with fumaric acid estersof coconut oil alcohols; viscosity index imnrovers such aspolymethacrylates; etc.

3,2 73,981 Patented Sept. 20, 1966 ICC The preferred dicarboxylic acidsfrom which the esters are made are those acids which contain at least 9carbon atoms between the respective carboxylic groups. It is verydesirable that the number of carbon atoms between the carboxylic groupsbe in the range from about 12 to 42. Specific examples of these acidsare the dimer of linoleic acid, dodecanedioic acid, anddicyclopentadiene dioic acid. While the foregoing acids are preferred,similar dicarboxylic acids such as VR-l described in US. 2,833,713 andD-SO described in U.S. 2,470,849 may be used. The dienoic or trienoicmonocarboxylic acid, that is polymerized to give the dicarboxylicpolymer, can have from 12 to 30 carbon atoms and must have at least twodouble bonds in its longest carbon chain, the bonds being separated by 3carbon atoms, e.g. 9,12-octadecadienoic acid and9,12,lS-octa-decatrienoic acid.

The mixture of high molecular weight unsaturated fatty acids comprisesmonomers, dimers, trimers and higher polymers in the ratio of from about45 to about 55% of a monomers and dimers fraction having a molecularweight in the range of from about 300 to 600, and from about 45% toabout 55% of a trimers and higher polymer fractions having a molecularweight in excess of 600. The fatty acid polymers result in part from athermal polymerization of fatty acid type constituents of the castoroil, and in part from other reactions, such as the intermolecularesterification, of such acid to form high molecular weight products. Theacid mixture, which is mainly a mixture of polymeric long chainpolybasic carboxylic acids, is further characterized by the followingspecifications:

Acid No -164- Saponification No. -186 Free fatty acids "percent" 75 to82 Iodine value 40 to 55 Nonsaponifiables percent 2.5 to 5 A fatty acidmixture such as above described is marketed by the W. C. HardestyCompany under the trade name D-SO Acids, and as VR-l Acids by Rohm &Haas Company.

Thus, as pointed out, a particularly desirable dicarboxylic acid to beused in forming the reaction product of the present invention is a dimerof linoleic acid.

The formation of this dimer acid may be illustrated as follows:

In general, the dimer acid of linoleic acid with which the presentinvention is concerned is a C dimer acid and is described in US. Patent2,424,5 88 issued July 29, 1947, and entitled Lubricant Composition;inventors, W. J. Sparks et al. It is to be understood that the dimeracid a is not necessarily 100% dimer acid. For example, the followingcompositions may be used:

Composition, Wt. Percent Thus, in essence, the presence invention uses amixture of A-t-B in an oleophilic fluid to improve anti-scuffingproperties where A is a polybasic acid, or a polybasic acid ester madepreferably by reacting the acid with C C monohydric alcohols; while B isa partial ester of a polyhydric alcohol and a fatty acid.

Specific examples of the foregoing category A compounds are: dimer acids(e g. dilinoleic acid); straight chain aliphatic dibasic acids, such asoxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid,pimelic acid, suberic acid, azelaic acid, sebacic acid and dodecanedioicacid; benzene polycarboxylic acids, such as phthalic acid, isophthalicacid, terephthalic acid, hemimellitic acid, trimellitic acid, trimesicacid, prehnitic acid, mellophanic acid, pyromellitic acid, benzenepentacarboxylic acid and mellitic acid; and others such as diphenicacid, diglycolic acid, d-tartaric acid and cis-4-cyclohexene acid.

Examples of alcohols (C C which may be used to .esterify these polybasicacids if desired are methanol,

ethanol, propanol, isopropanol, butanol, isobutanol, and pentanol. Otheralcohols are benzyl alcohol and cyclohexanol. These esters may also bemixed esters such as monomethyl monopropyl ester of the dimer of adicarboxylic acid such as the dimer of linoleic acid.

Compounds in category B include the C to C fatty acid partial esters ofaliphatic polyhydric alcohols having about 3 to 12, preferably 3 to 8,carbon atoms and about 2 to 8, e.g. 3 to 6 hydroxy .groups per molecule.Preferred materials are the monoand diesters of C to C alcohols having 3to 6 hydroxyl groups and prepared from C to C fatty acids. The abovetype of partial esters include the partial esters of the mono-dehydratedaliphatic polyhydric alcohols as well as partial esters ofnon-dehydrated aliphatic polyhydric alcohols. Examples of these partialesters are: sorbitan monoleate, glyceryl monooleate, pentaerythritolmonooleate, the dioleates of sorbitan, mannitan, pentaerythritol andrelated polyhydric alcohols, the corresponding partial stearic andpalmitic acid esters of these alcohols, and partial esters of thesealcohols made from mixtures of these fatty acids. Agents of this typeare well known in the art, e.g. U.S. 2,434,490 and 2,716,611.

It is important that at least two hydroxy groups and preferably more beon the carboxylic acid ester. Thus, partial esters of the followingcompounds could be used: mannitol, sorbitol, dulcitol, inositol,glucose, fructose, pentaerythritol and glycerol. Furthermore, partialesters of some of the above polyols in partly dehydrated form (e.g.sorbitan) could also be used. The preferred acid is oleic and moreparticularly the monooleate ester is preferred. This achieves oilsolubility while leaving the maximum number of free hydroxyl groupsleft. Of course, other fatty acids (e.g. 830 carbon atoms) and diesters(e.g. sorbitol dioleate) may also be used.

While the over-all objective of the present invention is to improve theanti-scuffing and anti-wear properties of fluids, one particularobjective of the present invention is to improve the lubricity ofdistillate fuels boiling in the range from about 50 to 750 F. Thus, inaccordance with the present invention, middle distillate compositionsare improved with respect to their lubricity by incorporating therein aneffective amount of a mixture of the present invention.

It is well known in the art to improve the quality of jet fuels byvarious refining techniques in order to remove from these fuelsundesirable constituents such as polar compounds, sulfur compounds, andnitrogen compounds. These compounds are removed in order to improveengine performance and lengthen the hours the engine can be operatedwithout major overhauling, but it has been found that when the viscosityof these fuels is relatively low and wherein certain impurities areremoved to below a maximum, the finished pure fuel lacks lubricity,which is essential in order to keep the engine parts from excessive wearand a relatively short life. These engine parts among others comprisethe fuel pumps, the gears, the bearings and any other parts whereinscuffing and wear is a problem.

Such fuels include aviation turbo-jet fuels, rocket fuels (MILR-25576B),kerosenes, diesel fuels and heating oils. Aviation turbo-jet fuels inwhich the mixture of the present invention may be used normally boilbetween about 50 and about 550 F. and are used in both military andcivilian aircraft. Such fuels are more fully defined by U.S. MilitarySpecifications MIL-F-5624F, MILF25656A, MIL-F-25554A, MILF25558B, andamendments thereto, and in ASTM D165562T. Kerosenes and heating oilswill normally have boiling ranges between about 300 and about 750 F. andare more fully described in ASTM Specification D396-48T and supplementsthereto, where they are referred to as No. 1 and No. 2 fuel oils. Dieselfuels in which the mixture of the present invention may be employed aredescribed in detail in ASTM Specification D97535T and later versions ofthe same specification.

Particularly desirable base fuels wherein the present additive mixturesare most effective are those base fuels wherein the viscosity is belowabout 3 centistokes and which fuels are substantially free of polarcompounds, sulfur compounds, and nitrogen compounds. In essence, theconcentration of these compounds is less than about 0.01% by weightwhich is secured when the jet fuel is highly refined, such as byhydrofining.

The additives of the present invention may be employed in conjunctionwith a variety of other additives commonly used in fuels such as thoseset forth above. Typical of these additives are rust inhibitors,anti-emulsifying agents, corrosion inhibitors, anti-oxidants,dispersants, dyes, dye stabilizers, haze inhibitors, antistatic agentsand the like. It will frequently be found convenient to prepare additiveconcentrates for use in the various types of fuels and thus add all ofthe additives simultaneously.

Thus, in accordance with the present invention, polybasic acids oresters of these acids, and a partial ester of a polyhydric alcoholcomprise new valuable additive mixtures for jet fuels. A particularlydesirable mixture comprises a dimer linoleic acid and sorbitanmonooleate.

If the additive mixtures of the present invention are used as anadditive concentrate, the concentrate may consist essentially of fromabout 25 to 75% of the addi tive mixture, the remainder being asatisfactory solvent such as kerosene, a Varsol, a naphtha and the like.The preferred concentrate contains about 50 to 60% of the additivemixture in the solvent.

When the additive mixture is used in conjunction with oleophilic liquid,the concentration may vary appreciably. For example, when the additivemixture is used in a fuel, the concentration is in the range from about0.001 to 1.0% by weight, preferably in the range from about 0.01 to 0.5%by weight. On the other hand, if the additive mixture is used with ahydrocarbon lubricating oil, the concentration may vary in the rangefrom about 0.001 to 4.9% by weight, preferably in the range from about0.1 to 2.0% by weight. It is preferred that the mole ratios of a partialester of a polyhydric alcohol and the dicarboxylic ester be about 1/1although the ratios may vary from 0.5/1 to 1.5/1.

In ord r to further illustrate the invention, a number of tests werecarried out using the additives of the present invention in base jetfuels and the load carrying capacity of the fuels determined.

As shown by the data below, the addition of 0.2% of the additive mixtureincreases the anti-scufiing properties of jet fuel as measured by theRyder Gear Test (Ryder, E. A., ASTM Bulletin 184, 41 (1952)). Theratings represent the load in pounds/ inch of tooth width to produce agiven amount (22 /2%) of gear scufiing.

EFFECT OF C DIMER ACID AND SORBITAN MONOOLATE ON RYDER GEAR PERFORM-ANCE OF JET FUEL Ryder rating Additive in jet fuel: 1 (lbs/in.)

None Ca. 400 01% C dimer acid-0.1% sorbitan monooleate 1790 0.1% C dimeracid 480 0.2% sorbitan monooleate 810 1 High isoparafiinlc fuel of375500 F. boiling range, high thermal stability, W freezing point andlow sulfur content.

As seen by the data in the above table, the addition of C dimer acid andsorbitan monooleate to jet fuel increased the Ryder scufii rating fromabout 400 lbs/in. to 1790 lbs/in. This is a substantial increase.Furthermore, it can also be seen that dimer acid alone has nosignificant eifect and that sorbitan monooleate by itself is rathermediocre.

The additive mixtures of the present invention, as pointed outheretofore, are also very effective in increasing the load carryingcapacity of other fuels such as kerosene, and synthetic oils as well asmineral lubricating oils. The synthetic oils will include diester oilssuch as di(2-ethylhexyl) sebacate; complex ester oils and silicone oils;sulfide esters; organic carbonates; and other synthetic oils known tothe art.

What is claimed is:

-1. A hydrocarbon middle distillate boiling in the range from to about750 F. containing dissolved therein between about 0.001 and about 1.0wt. percent of an additive mixture comprising a polycarboxylic acid ofbetween about 9 and about 42 carbon atoms per molecule between thecarboxylic acid groups and a partial ester of a polyhydric alcohol ofbetween about 3 and about 8 carbon atoms per molecule and containingbetween about 3 and about 6 hydroxyl groups per molecule and a C to Cfatty acid.

2. A hydrocarbon middle distillate as in claim 1 wherein the additivemixture is present in an amount between about 0.01 and about 0.5 wt.percent.

3. A hydrocarbon middle distillate as in claim 2 wherein the distillateis a jet fuel.

4. A hydrocarbon middle distillate as defined by claim 1 wherein saidpolycarboxylic acid is the dimer of linoleic acid.

5. A hydrocarbon middle distillate as defined by claim 1 wherein saidpolycarboxylic acid is dodecanedioic acid.

6. A hydrocarbon middle distillate as defined by claim 1 wherein saidpolycarboxylic acid is dodecanedioic dioic acid.

7. A hydrocarbon middle distillate as defined by claim 1 wherein saidpolycarboxylic acid is a dimer of linoleic acid and said partial esteris sorbitan monooleate.

References Cited by the Examiner UNITED STATES PATENTS 1,463,092 7/1923Pelly 252-56 2,334,158 11/1943 Von Fuchs et a1 25256 2,394,909 2/1946Gleason 252-56 2,424,588 7/1947 Sparks et al 25256 2,767,144 10/1956Gottshall et a1. 44-66 2,833,713 5/1958 Lemmon et al. 252-32.7

DANIEL E. WYMAN, Primary Examiner.

J. E. DEMPSEY, P. KONOPKA, Assistant Examiners.

1. A HYDROCARBON MIDDLE DISTILLATE BOILING IN THE RANGE FROM 50* TOABOUT 750*F. CONTAINING DISSOLVED THEREIN BETWEEN ABOUT 0.001 AND ABOUT1.0 WT. PERCENT OF AN ADDITIVE MIXTURE COMPRISING A POLYCARBOXYLIC ACIDOF BETWEEN ABOUT 9 AND ABOUT 42 CARBON ATOMS PER MOLECULE BETWEEN THECARBOXYLIC ACID GROUPS AND A PARTIAL ESTER OF A POLYHYDRIC ALCOHOL OFBETWEEN ABOUT 3 AND ABOUT 8 CARBON ATOMS PER MOLECULE AND CONTAININGBETWEEN ABOUT 3 AND ABOUT 6 HYDROXYL GROUPS PER MOLECULE AND A C12 TOC22 FATTY ACID.